Driveshaft problems

[lukecp]

Today me and a friend went and put 3 new U-joints and a new carrier bearing in my '72 LWB. After putting everything together, we took it for a test run. Going down a paved road, it now vibrates REALLY bad. It is also makes a low, deep noise from the vibration. I think this is because when we took the driveshaft apart to put the carrier bearing in, we didn't put the to halves together in the same place as they were before, and this threw off the balance. Now i can barely drive the truck over 25mph. But the upside is that the U joints and carrier bearing fixed all of the problems with strange noises i was haveing before. So, how should i go about fixing this? Here is what i have though of so far:

1. Go to the junkyard and take my chances with a used driveshaft
2. Find a place that balances driveshafts (i doubt there is one around here)
3. I once heard that to balance a driveshat, you can squirt about 1/2 a tube of grease from a grease gun inside the tube, and it will balance it as you drive. It sounds like it might work, but i dunno if i want to try it or not.

Thanks for any help.